Re: Pumpkinguy on drip irrigation

In a message dated 3/16/99 12:01:14 PM Eastern Standard Time,
chrisk@ci.salinas.ca.us writes:

<< 
 Curious if you have any special trick for treatment of powdery mildew. I
 live on the Central Coast of California-quite damp. I always have a problem
 with it. THanks.
 
 > -----Original Message-----
 > From: owner-pumpkins@mallorn.com [o*@mallorn.com]On
 > Behalf Of Stewart Deans
 > Sent: Tuesday, March 16, 1999 2:08 AM
 > To: pumpkins@mall >>
Christine,
   Dr. Meg McGrath of cornell university out on Long Island in New York is one
of the foremost researchers on the problems of powdery mildew on vine crops.
She came out to my patch last year.....thank God before the powdery mildew
hit. Actually, the Atlantic Giant ( being in the C. Maxima family) is somewhat
resistant to powdery mildew. I know it is hard to believe, but C.Pepo (regular
field pumpkins) get it much worse. I have found that my field pumpkins get it
whether it is wet or a dry year and I spray with a variety of chemicals.
Stress seems to trigger the onset of powdery mildew somewhat. The stress of
setting fruit and the plant getting older seems to be a factor. New growth
doesn't seem to get it as bad as the older growth. I start to see powdery
mildew in my fields around August...give or take a couple weeks. Some areas
get it later than others. What I try to do is delay a major outbreak and allow
the plants to mature their fruit before the mildew really sets in....the
mildew always wins in the end , with the field pumpkins. Cornell and Harris
seeds have been developing powdery mildew resistant varieties of field
pumpkins. I dare say, it would be much easier to increase the mildew
resistance in the AGiant for it already exhibits some resistance. Chemical
control is subject to debate as to the chemicals used and the timing of
sprays. Generally, you are better to protect against disease before it
happens, however, there is a problem. There are two major strains of powdery
mildew in our area and both are showing resistance to the available chemicals.
It is felt by some, that Benlate and Bayleton may only be partially effective
on the first application and subsequent applications may be ineffective. This
is why Meg McGrath likes to scout the fields and wait until the very first
signs of invasion...usually on the underside of the leaves. Then hit them.
Bravo (chlorothalonil), Bayleton and Benlate are the chemicals of choice for
the most part. None of them work well alone. There is a synergistic effect by
using Bravo/Bayleton together. Then alternate with Bravo/Benlate the next
week. In some states, Quadris is registered for vinecrops.....you don't want
to know what that stuff costs. For the organic growers.....I'm not sure?????
Maybe seaweed sprays or sulfur. A good hard spray of water on the leaves(not
to the point of mechanical damage) may knock some of it off. Pruning to allow
for better circulation might help....thin out the jungle. As the plant gets
older, it is inevitable that some leaves will get old and ratty looking....you
can prune the real bad ones out to allow room for the newer tertiary growth.
No matter how well you prune, there is always some new growth that pops out of
somewhere that can take up the space vacated by the old dead leaves. People in
the warm climate areas seem to have more problems with the leaves looking old
, early....too much stress. It seems like up North, it is easier to keep the
leaves greener and in better shape for a longer period of time.Good luck
                                                              pumkinguy 

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